Glycosylphosphatidylinositol Anchor Biosynthesis Pathway-Related Protein GPI7 Is Required for the Vegetative Growth and Pathogenicity of Colletotrichum graminicola

Tolerance Mechanisms and Removal Efficiency of Chlorella pyrenoidosa in Treating 3-Fluorophenol Pollution

This study investigates the growth tolerance mechanisms of Chlorella pyrenoidosa to 3-fluorophenol and its removal efficiency by algal cells. Our results indicate that C. pyrenoidosa can tolerate up to 100 mg/L of 3-fluorophenol, exhibiting a significant hormesis effect characterized by initial inhibition followed by promotion of growth. In C. pyrenoidosa cells, the activities of superoxide dismutase (SOD) and catalase (CAT), as well as the levels of malondialdehyde (MDA) and reactive oxygen species (ROS), were higher than or comparable to the control group. Metabolic analysis revealed that the 3-fluorophenol treatment activated pathways, such as glycerol phospholipid metabolism, autophagy, glycosylphosphatidylinositol (GPI)-anchored protein biosynthesis, and phenylpropanoid biosynthesis, contributed to the stabilization of cell membrane structures and enhanced cell repair capacity. After 240 h of treatment, over 50% of 3-fluorophenol was removed by algal cells, primarily through adsorption. Thus, C. pyrenoidosa shows potential as an effective biosorbent for the bioremediation of 3-fluorophenol.

Plant- and Animal-Derived Dietary Sources of Phosphatidylcholine Have Differential Effects on Immune Function in The Context of A High-Fat Diet in Male Wistar Rats

BACKGROUND

Phosphatidylcholine (PC) derived from eggs has been shown to beneficially modulate T cell response and intestinal permeability under the context of a high-fat diet.

OBJECTIVES

The objective of this study was to determine whether there is a differential effect of plant and animal-derived sources of PC on immune function.

METHODS

Four-week-old male Wistar rats were randomly assigned to consume 1 of 4 diets (n = 10/group) for 12 wk, all containing 1.5 g of total choline/kg of diet but differing in choline forms: 1-Control Low-Fat [CLF, 20% fat, 100% free choline (FC)]; 2-Control High-Fat (CHF, 50% fat, 100% FC); 3-High-Fat Egg-derived PC (EPC, 50% fat, 100% Egg-PC); 4-High-Fat Soy-derived PC (SPC, 50% fat, 100% Soy-PC). Immune cell functions and phenotypes were measured in splenocytes by ex vivo cytokine production after mitogen stimulation and flow cytometry, respectively.

RESULTS

The SPC diet increased splenocyte IL-2 production after PMA+I stimulation compared with the CHF diet. However, the SPC group had a lower proportion of splenocytes expressing the IL-2 receptor (CD25+, P < 0.05). After PMA+I stimulation, feeding EPC normalized splenocyte production of IL-10 relative to the CLF diet, whereas SPC did not (P < 0.05). In mesenteric lymph node lymphocytes, the SPC diet group produced more IL-2 and TNF-α after PMA+I stimulation than the CHF diet, whereas the EPC diet group did not.

CONCLUSIONS

Our results suggest that both egg- and soy-derived PC may attenuate high-fat diet-induced T cell dysfunction. However, egg-PC enhances, to a greater extent, IL-10, a cytokine involved in promoting the resolution phase of inflammation, whereas soy-PC appears to elicit a greater effect on gut-associated immune responses.

Plant immunity suppression by an β-1,3-glucanase of the maize anthracnose pathogen Colletotrichum graminicola

BACKGROUND

Many phytopathogens secrete a large number of cell wall degrading enzymes (CWDEs) to decompose host cell walls in order to penetrate the host, obtain nutrients and accelerate colonization. There is a wide variety of CWDEs produced by plant pathogens, including glycoside hydrolases (GHs), which determine the virulence, pathogenicity, and host specificity of phytopathogens. The specific molecular mechanisms by which pathogens suppress host immunity remain obscure.

RESULT

In this study, we found that CgEC124 encodes a glycosyl hydrolase with a signal peptide and a conserved Glyco_hydro_cc domain which belongs to glycoside hydrolase 128 family. The expression of CgEC124 was significantly induced in the early stage of Colletotrichum graminicola infection, especially at 12 hpi. Furthermore, CgEC124 positively regulated the pathogenicity, but it did not impact the vegetative growth of mycelia. Ecotopic transient expression of CgEC124 decreased the disease resistance and callose deposition in maize. Moreover, CgEC124 exhibited the β-1,3-glucanase activity and suppresses glucan-induced ROS burst in maize leaves.

CONCLUSIONS

Our results indicate that CgEC124 is required for full virulence of C. graminicola but not for vegetative growth. CgEC124 increases maize susceptibility by inhibiting host reactive oxygen species burst as well as callose deposition. Meanwhile, our data suggests that CgEC124 explores its β-1,3-glucanase activity to prevent induction of host defenses.

Effector secretion and stability in the maize anthracnose pathogen Colletotrichum graminicola requires N-linked protein glycosylation and the ER chaperone pathway

N-linked protein glycosylation is a conserved and essential modification mediating protein processing and quality control in the endoplasmic reticulum (ER), but how this contributes to the infection cycle of phytopathogenic fungi is largely unknown. In this study, we discovered that inhibition of protein N-glycosylation severely affected vegetative growth, hyphal tip development, conidial germination, appressorium formation, and, ultimately, the ability of the maize (Zea mays) anthracnose pathogen Colletotrichum graminicola to infect its host. Quantitative proteomics analysis showed that N-glycosylation can coordinate protein O-glycosylation, glycosylphosphatidylinositol anchor modification, and endoplasmic reticulum quality control (ERQC) by directly targeting the proteins from the corresponding pathway in the ER. We performed a functional study of the N-glycosylation pathway-related protein CgALG3 and of the ERQC pathway-related protein CgCNX1, which demonstrated that N-glycosylation of ER chaperone proteins is essential for effector stability, secretion, and pathogenicity of C. graminicola. Our study provides concrete evidence for the regulation of effector protein stability and secretion by N-glycosylation.

In Silico Evaluation, Phylogenetic Analysis, and Structural Modeling of the Class II Hydrophobin Family from Different Fungal Phytopathogens

The class II hydrophobin group (HFBII) is an extracellular group of proteins that contain the HFBII domain and eight conserved cysteine residues. These proteins are exclusively secreted by fungi and have multiple functions with a probable role as effectors. In the present study, a total of 45 amino acid sequences of hydrophobin class II proteins from different phytopathogenic fungi were retrieved from the NCBI database. We used the integration of well-designed bioinformatic tools to characterize and predict their physicochemical parameters, novel motifs, 3D structures, multiple sequence alignment (MSA), evolution, and functions as effector proteins through molecular docking. The results revealed new features for these protein members. The ProtParam tool detected the hydrophobicity properties of all proteins except for one hydrophilic protein (KAI3335996.1). Out of 45 proteins, six of them were detected as GPI-anchored proteins by the PredGPI server. Different 3D structure templates with high pTM scores were designed by Multifold v1, AlphaFold2, and trRosetta. Most of the studied proteins were anticipated as apoplastic effectors and matched with the ghyd5 gene of Fusarium graminearum as virulence factors. A protein-protein interaction (PPI) analysis unraveled the molecular function of this group as GTP-binding proteins, while a molecular docking analysis detected a chitin-binding effector role. From the MSA analysis, it was observed that the HFBII sequences shared conserved 2 Pro (P) and 2 Gly (G) amino acids besides the known eight conserved cysteine residues. The evolutionary analysis and phylogenetic tree provided evidence of episodic diversifying selection at the branch level using the aBSREL tool. A detailed in silico analysis of this family and the present findings will provide a better understanding of the HFBII characters and evolutionary relationships, which could be very useful in future studies.

Genome Sequence Resource of a Colletotrichum graminicola Field Strain from China

The maize anthracnose stalk rot and leaf blight diseases caused by the fungal pathogen Colletotrichum graminicola is emerging as an important threat to corn production worldwide. In this work, we provide an improved genome assembly of a C. graminicola strain (TZ-3) by using the PacBio Sequel II and Illumina high-throughput sequencing technologies. The genome of TZ-3 consists of 36 contigs with a length of 59.3 Mb. After correction and evaluation with the Illumina sequencing data and BUSCO, this genome showed a high assembly quality and integrity. Gene annotation of this genome predicted 11,911 protein-coding genes, among which 983 secreted protein-coding genes and 332 effector genes were predicted. Compared with previous genomes of C. graminicola strains, TZ-3 genome is superior in nearly all parameters. The genome assembly and annotation will enhance our knowledge of the genetic makeup of the pathogen and molecular mechanisms underlying its pathogenicity and will provide valuable insights into genome variation across different regions. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Efficient microalgal lipid production driven by salt stress and phytohormones synergistically

In this study, a novel method of coupling phytohormones with saline wastewater was proposed to drive efficient microalgal lipid production. All the six phytohormones effectively promoted microalgae growth in saline wastewater, and further increased the microalgal lipid content based on salt stress, so as to achieve a large increase in microalgal lipid productivity. Among the phytohormones used, abscisic acid had the most significant promoting effect. Under the synergistic effect of 20 g/L salt and 20 mg/L abscisic acid, the microalgal lipid productivity reached 3.7 times that of the control. Transcriptome analysis showed that differentially expressed genes (DEGs) of microalgae in saline wastewater were mainly up-regulated under the effects of phytohormones except brassinolide. Common DEGs analysis showed that phytohormones all regulated the expression of genes related to DNA repair and substance synthesis. In conclusion, synergistic effect of salt stress and phytohormones can greatly improve the microalgal lipid production efficiency.

Systematic identification and functional characterization of the CFEM proteins in poplar fungus Marssonina brunnea

Proteins containing Common in Fungal Extracellular Membrane (CFEM) domains uniquely exist in fungi and play significant roles in their whole life history. In this study, a total of 11 MbCFEM proteins were identified from Marssonina brunnea f. sp. multigermtubi (MULT), a hemibiotrophic pathogenic fungus on poplars that causes severe leaf diseases. Phylogenic analysis showed that the 11 proteins (MbCFEM1-11) were divided into three clades based on the trans-membrane domain and the CFEM domain. Sequence alignment and WebLogo analysis of CFEM domains verified the amino acids conservatism therein. All of them possess eight cysteines except MbCFEM4 and MbCFEM11, which lack two cysteines each. Six MbCFEM proteins with a signal peptide and without trans-membrane domain were considered as candidate effectors for further functional analysis. Three-dimensional (3D) models of their CFEM domains presented a helical-basket structure homologous to the crucial virulence factor Csa2 of Candida albicans. Afterward, four (MbCFEM1, 6, 8, and 9) out of six candidate effectors were successfully cloned and a yeast signal sequence trap (YSST) assay confirmed their secretion activity. Pathogen challenge assays demonstrated that the transient expression of four candidate MbCFEM effectors in Nicotiana benthamiana promoted Fusarium proliferatum infection, respectively. In an N. benthamiana heterogeneous expression system, MbCFEM1, MbCFEM6, and MbCFEM9 appeared to suppress both BAX/INF1-triggered PCD, whereas MbCFEM8 could only defeat BAX-triggered PCD. Additionally, subcellular localization analysis indicated that the four candidate MbCFEM effectors accumulate in the cell membrane, nucleus, chloroplast, and cytosolic bodies. These results demonstrate that MbCFEM1, MbCFEM6, MbCFEM8, and MbCFEM9 are effectors of M. brunnea and provide valuable targets for further dissection of the molecular mechanisms underlying the poplar-M. brunnea interaction.